Air cooled internal combustion engine



Oct. 16, 1956 E. FLATZ ETAL AIR COOLED INTERNAL COMBUSTION ENGINE 2 Sheets-Sheet 1 Filed May 9, 1955 W n/raps J se 7 00:..16, 1956 E, FLATZ ET AL 2,766,741

AIR COOLED INTERNAL COMBUSTION ENGINE Filed May 9, 1955 2 Sheets-Sheet 2 lNVfNTOIPS and Jose 'ue/ 7:4, @GM/T COOLED INTERNAL COMBUSTION ENGINE Emil Fiatz, Bergisch Gladbach, Germany, and Josef T: States Patent Hiivel, deceased, late of Koln-Delibruck, Germany, by

Margareta E. Hove], executrix, Koln-Dellbruck, Germany, assignors to Klockner-Humboldt-Deutz Aktiengesellschaft, Koln, Germany Application May 9, 1955, Serial No. 518,708 Claims priority, application Germany May 12, 1954 8 Claims. (Cl. 12341.67)

The present invention relates to internal combustion engines and, more particularly, is directed to air-cooled slot-controlled two-stroke cycle internal combustion engines in which the cylinder and the cylinder head are provided with fins extending all the way through.

With air-cooled slot-controlled two-stroke cycle internal combustion engines, difliculties are still encountered concerning a fully satisfactory cooling of that portion which comprises the exhaust passages.

it is, therefore, an object of the present invention to provide an air-cooled internal combustion engine which will overcome the above mentioned drawbacks.

It is another object of this invention to provide a twostroke cycle internal combustion engine with cooling fins in such a manner that the cooling of the section containing the discharge passages will be greatly improved.

It is also an object of this invention to provide an internal combustion engine of the above type with cooling fins in such a manner that the cooling air passing around the cylinder is guided from all sides concentrically toward the discharge passages thereby bringing about a highly effective cooling of said discharge passages.

These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawings, in which:

Fig. 1 illustrates a cylinder and cylinder head of an air-cooled slot-controlled two-stroke cycle internal combustion engine according to the invention, said cylinder and cylinder head being viewed against the discharge side and being surrounded by the engine casing shown in section.

Fig. 2 is a top view of the arrangement shown in Fig. 1 with the hood on the engine casing removed.

Fig. 3 shows the cylinder and cylinder head of Fig. 1 seen in the direction of the arrow in Fig. 2.

The primary feature of the present invention consists in that the cylinder and the cylinder head are provided with cooling fins which are symmetrically arranged with regard to the vertical plane of symmetry through the cylinder axis, while the cooling fins on the discharge side of the cylinder on one side of the said plane of symmetry form a V with the corresponding cooling fins on the other side of said plane of symmetry. The arrangement is such that the legs of the Vs formed by the fins on opposite sides of the exhaust passages taper toward the exhaust passages so that when the engine is in upright position the legs of the Vs formed by the fins above the discharge passages extend from the apices of said Vs upwardly whereas with the fins below the exhaust passages, the legs extend from the apices of the respective Vs downwardly. It will be clear that in this way the cooling air is concentrically guided by the fins from all sides toward the exhaust passages.

Referring now to the drawings in detail, the arrangement shown therein comprises a cylinder 1 with inserted sleeve, which cylinder is longitudinally displaceably inserted in the engine casing 2. The engine casing simul- 2,766,741 Patented Oct. 16, 1956 taneously serves as a kind of cowl for guiding the cooling air around the cylinder. The engine casing is provided with three fitting bores 3, 4 and 4 in which the cylinder 1 is guided. The engine casing ends in a plane bb above the control passages of the cylinder. A hood 5 covering the cylinder head is mounted on the engine casing 2 and is threadedly connected thereto by means of bolts 6. The hood 5 similar to the engine casing 2 serves for guiding the cooling air around the cylinder head. Fig. 2 clearly illustrates how the engine casing 2 and hood 5 extend about the cylinder and cylinder head. The passage for the air entrance is designated with the reference numeral 7 whereas the passage for the air exit is designated with the reference numeral 8. While the air entrance passage 7 extends over the entire height of the cylinder with uniform width as shown in Fig. 2, this is not the case with regard to the air exit passage 8 the contour of which is shown in Fig. 1 by dot dash lines.

The cylinder 1 is suspended on the hood 5 by means of threaded bolts 10. The lower end of cylinder 1 is guided in the fitting bore 3 which also contains a rubber gasket 11. The two-stroke cycle internal combustion engine is of a type operating with crank case scavenging. The intake passages 12 (Fig. 3) for the crank case scavenging pump are located in the cylinder wall and are controlled by the working piston. The intake passages 12 are located in a plane below the discharge passages 13. The discharge passages 13 are arranged in conformity with a unilateral reversing scavenging. The scavenging channels 14 are clearly visible in Fig. 3.

The intake passages 12 lead on the outside of the cylinder wall into a gallery channel 15 surrounding the cylinder. The gallery channel 15 is defined by flanges 16 and 17 of the engine casing which flanges are provided with the above mentioned fitting bores 4, 4 for fittingly receiving the cylinder. In this way the gallery channel 15 is closed toward the outside by the cylindrical inner wall of the engine casing. The gallery channel 15 is provided with an intake passage 18 (Fig. 1) in the engine casing 2. The intake passage 18 is connected to a connection 19 pertaining to an intake filter not shown in the drawing.

The cylinder-cylinder head arrangement according to the present invention is particularly characterized in that the cooling fins therefor are arranged symmetrically with regard to the vertical plane c-c (Fig. 2) passing through the axis of said cylinder-cylinder head arrangement and representing the plane of symmetry for the discharge passages. In the embodiment illustrated in the drawings, the cylinder and the cylinder head are made of a single piece. It is, however, understood that the invention is also applicable to a cylinder-cylinder head arrangement, in which the cylinder and the cylinder head are separate from each other. On the discharge or exhaust side of the cylinder, the cooling fins 20 and 21 are arranged so that the cooling fins 20 on each side of the above mentioned plane of symmetry together form Vs. Similarly the fins 21 are arranged in V-shaped manner. As will be evident from Fig. 1, the arrangement is such that the legs of the Vs formed by the fins on opposite sides of the exhaust passages 13 taper toward the exhaust passages 13 so that when the engine is in upright position, the legs of the Vs formed by the fins 20 extend from the apices of said Vs upwardly, whereas with the fins below the exhaust passages 13, the legs extend from the apices of the respective Vs downwardly. At the level of the discharge passages 13, cooling fins 23 are provided which are located in a plane perpendicular to the longitudinal axis of the cylinder-cylinder head arrangement, That cylinder surface of the cylinder-cylinder head arrangement which is opposite to the exhaust passages 13 and is located at an area corresponding to the area covered by the fins 21 is provided with fins 24. In contrast to the fins 21, however, the fins 24 are located in planes perpendicular to the longitudinal axis of said cylinder-cylinder head arrangement. In some instances it is advantageous to provide heat conducting ribs or fins in the vertical plane of symmetry cc passing through the cylinder axis and to extend said heat conducting ribs or fins to the cooling fins. Such heat conducting ribs or fins are indicated in Figs. 1 and 3 by dot dash lines and are designated in Fig. l with the reference numerals 25 and 26 and are designated in Fig. 3 with the reference numerals 27 and 2.3. At those points where V-shaped fins and horizontal fins are arranged adjacent each other, supporting ribs 29 are arranged therebetween as shown in Figs. 1 and 3.

In order that the cooling of the cylinder within the area of the exhaust passages 13 will not be harmfully affected by the gallery channel 15, the gallery channel 15 is interrupted within the area of the exhaust passages 13 so that the V-shaped cooling fins 21 can be extended up to the exhaust passages 13.

The invention is not limited to a certain type of twostroke cycle internal combustion engines but may advantogeously also be applied to gas-air compressing twostrolte cycle internal combustion engines and also to fuel injection internal combustion engines.

It is also to be understood that the present invention is, by no means, limited to the particular construction illustrated in the drawings but also comprises any modifications within the scope of the appended claims.

What we claim is:

1. In an air-cooled slot-controlled two-stroke cycle internal combustion engine, the combination of: a cylinder provided with exhaust passage means, a cylinder head connected to said cylinder, and cooling fins on said cylinder and cylinder head, the cooling fins on said cylinder being aligned with the respective adjacent cooling fins on said cylinder head, the cooling fins on said cylinder and cylinder head being arranged symmetrically with regard to the plane passing through the longitudinal axis of said cylinder and representing the plane of symmetry of said exhaust passage means, the cooling fins on that side of the cylinder which contains said exhaust passage means being located so that the fins on one side of said plane respectively form Vs with the fins on the other side of said plane, the arrangement being such that the legs of the Vs formed by the fins located on opposite sides of said exhaust passage means taper toward said exhaust passage means.

2. in an air-cooled slot-controlled two-stroke cycle internal combustion engine, the combination of: a cylinder provided with exhaust passage means on one side thereof, a cylinder head connected to said cylinder, and cooling fins on said cylinder and cylinder head, the cooling fins on said cylinder being aligned with the respective adjacent cooling fins on said cylinder head, the cooling fins on said cylinder and cylinder head being arranged symmetrically with regard to the plane passing through the longitudinal axis of said cylinder and representing the plane of symmetry of said exhaust passage means, the cooling fins on that side of the cylinder which contains said exhaust passage means being located so that the fins on one side of said plane respectively form Vs with the fins on the other side of said plane, the arrangement being such that the legs of the Vs formed by the fins located on opposite sides of the exhaust passage means taper toward the exhaust passage means, the fins arranged on that cylinder head side which is located opposite that side which contains the exhaust passage means likewise. forming V5 with those adjacent fins on the cylinder which are located between said cylinder head and the plane passing perpendicular to the longitudinal t cooling fins. on said' cylinder being aligned with the respective adjacent cooling fins on said cylinder head, a second group of cooling fins on said cylinder on the opposite side of said exhaust passage means, the cooling fins of said first and second group being arranged symmetrically, with regard to the piano passing through the longitudinal axis of said cylinder and representing the plane of symmetry of said exhaust passage means, the

cooling fins of said first and second group being located so. that the fins. on. one side of said plane respectively form Vs with. the. fins: on the other side of said plane, the arrangement being such that the legs of the Vs formed by the fins located on opposite sides of said exhaust passage means taper toward said exhaust passage means, and a third group oi cooling fins arranged between said first and second group within the area confined by the plane passing through that side of the exhaust passage means which faces the cylinder head and by the plane passing through the opposite side of said exhaust passage means, the fins of saidv third group having their major surfaces arranged substantially perpendicular to the longitudinal. axis. of said cylinder.

4. An air-cooled slot-controlled two-stroke cycle internal. combustion engine according to claim 3, in which the fins of said third group of cooling fins also extend over that side of the cylinder which is opposite said exhaust passage: means.

5. An air-cooled slot-controlled two-stroke cycle internal combustion engine according to claim 3, which includes. a fourth group of cooling fins arranged on that cylinder portion which is located opposite the cylinder portion provided with sm'd second group of fins.

6... In an air-cooled slot-controlled two-stroke cycle internal. combustion engine, the combination of: a cylinder provided with exhaust passage means, a cylinder head connected to said cylinder, cooling fins on said cylinder and cylinder head, the cooling fins on said cylinder being aligned. with the respective adjacent cooling fins on said cylinder head, the cooling fins on said cylinder and. cylinder head being arranged symmetrically with regard to the plane passing through the longitudinal axis. of said cylinder and. representing the plane of symmetry of said exhaust passage means, the cooling fins on that side of the cylinder which contains said exhaust passage means being located so that the fins on one side of said plane respectively form Vs with the fins on the other side of said plane, the arrangement being such that the egs of the Vs formed by the fins located on opposite sides of said exhaust passage means taper toward said exhaust passage means, and heat conducting ribs arranged on said cylinder and cylinder head and located in said plane of symmetry, said cooling fins extending up to said heat conducting ribs.

7. In an air-cooled slot-controlled two-stroke cycle internal combustion engine, the combination of: a cylinder provided with. exhaust passage means on one side thereof, a cylinder head connected to'said cylinder, first cooling fins on said cylinder and. cylinder head on that one side of said exhaust passage means which faces said cylinder head, the cooling fins on said cylinder being aligned with the respective adjacent cooling fins on said cylinder head, second cooling fins on said cylinder on the opposite side of said exhaust passage means, said first and second cooling fins being arranged symmetrically with regard to the plane passing through the longitudinal axis or said cylin-. der and representing the plane of symetr of said exhaust. passage means, said. first and second cooling fins being located so that the fins on one side of said plane respectively form Vs with the fins on the other side of said plane, the arrangement being; such that the legs of the Vs formed by the fins located on the opposite sides of said exhaust passage means taper toward said exhaust passage means, third cooling fins arranged between said first and second cooling fins Within the area confined by the plane passing through that side of the exhaust passage means which faces the cylinder head and by the plane passing through the opposite side of said exhaust passage means, said third fins having their major surfaces arranged substantially perpendicular to the longitudinal axis of said cylinder, and supporting ribs arranged between and interconnecting adjacent first and third fins.

8. In an air-cooled slot-controlled two-stroke cycle internal combustion engine provided with an engine casing having displaceably mounted therein a cylinder and a cylinder head connected thereto and also provided with a crank case, the combination of: cooling fins on said cylinder and cylinder head, the cooling fins on said cylinder being aligned with the respective adjacent cooling fins on said cylinder head, the cooling fins on said cylinder and cylinder head being arranged symmetrically with regard to the plane passing through the longitudinal axis of said cylinder and representing the plane of sym metry of said exhaust passage means, the cooling fins on that side of the cylinder which. contains said exhaust passage means being located so that the fins on one side of said plane respectively form Vs with the fins on the other side of said plane, the arrangement being such that the legs of the VS formed by the fins located on opposite sides of said exhaust passage means taper toward said exhaust passage means, and channel means arranged for communication with the intake passage means of a crank case scavenging pump and surrounding said cylinder over a section between said exhaust passage means and said crank case while being interrupted at a section adjacent said exhaust passage means to thereby allow the V-shaped cooling fins to extend up to said exhaust passage means.

References Cited in the file of this patent FOREIGN PATENTS 291,310 Switzerland Sept. 1, 1953 

